Substituted cinnamic acids and cinnamic acid esters

ABSTRACT

The invention relates to substituted cinnamic acids and cinnamic acid esters of formula (I), wherein X represents F, Cl or J and R 1  and R 2  are the same or different and represent hydrogen, an optionally substituted C 1 -C 10 -alkyl radical or an optionally substituted benzyl radical. Substituted indanone carboxylic acid esters are produced using said substituted cinnamic acid and cinnamic acid ester in a technically simple and non-dangerous manner as far as safety is concerned.

BACKGROUND OF THE INVENTION

The present invention relates to substituted cinnamic acids and cinnamicacid esters, to a process for their preparation and to their use forsynthesizing insecticide precursors.

The synthesis of insecticides is of high importance. Importantintermediates in this synthesis are the substituted indanonecarboxylicacid esters and their salts.

WO 95/29171, for example, discloses a process for preparing oxadiazineswhich are used in the field of crop protection for controllingarthropods. In the multistep preparation process, use is made, interalia, of substituted indanonecarboxylic acid ester intermediates. Thesynthesis of the substituted indanonecarboxylic acid esters comprises aFriedel-Crafts reaction of para-substituted phenylacetyl halides withethylene in the presence of a Lewis acid and an inert solvent withformation of a 2-tetralone of the formula A, where R¹ represents F. Clor C₁-C₃-fluoroalkoxy,

the reaction of the compound A with peroxycarboxylic acids withformation of substituted arylpropionic acids of the formula B,

the esterification of the substituted arylpropionic acids of the formulaB with C₁-C₃-alcohols in the presence of an acid catalyst with formationof the substituted arylpropionic acid esters of the formula C, where R″represents C₁-C₃-alkyl,

and the reaction of the compounds C with a base with ring closure andformation of the substituted indanonecarboxylic acid ester of theformula D

This synthesis of the substituted indanonecarboxylic acid esters has thedisadvantage that the addition of from 0.9 to 1.5 molar equivalents of aLewis acid, such as, for example, aluminum trichloride, is required inthe Friedel-Craft reaction for the reaction of the phenylacetyl halideswith ethylene. As a consequence, large amounts of salts are producedduring work-up of the reaction mixture, and thus corresponding volumesof contaminated waste water. Additionally, this synthesis requires theuse of peroxycarboxylic acids, such as, for example, peroxyacetic acid,for cleaving the 2-tetralone. For this purpose, the peroxycarboxylicacids have to be employed in an amount of from 2.5 to 3.5 molarequivalents. If the reaction is carried out on an industrial scale, thiscauses safety risks. Therefore, the reaction temperature has to beexactly maintained and, furthermore, the addition of theperoxycarboxylic acid has to be controlled accurately to avoid anaccumulation of excessive amounts of excess peroxycarboxylic acid in thereaction system.

It is furthermore known from J. Pharm. Sci. 67(1) 1978, 81, to preparethe chloro-substituted indanonecarboxylic acid ester5-chloro-2-methoxycarbonyl-1-indanone starting from3-chlorobenzaldehyde. Here, 3-chlorobenzaldehyde is initially reacted inpyridine with malonic acid to give 3-chlorocinnamic acid. Followinghydrogenation of the ethylenic double bond and cyclization to the5-chloro-1-indanone, the latter is then reacted with dimethyl carbonatein the presence of sodium hydride and benzene as solvent to give5-chloro-2-methoxycarbonyl-1-indanone. This synthesis method has thedisadvantage of the multistep mechanism which considerably increases thelikelihood of the formation of various by-products, which is reflectedin only a low yield of 48%. Additionally, the total reaction requiresthe repeated use of substances such as sodium hydride and benzene, whichare expensive, problematic with respect to safety or hazardous tohealth.

Chemical Abstracts 97, 1982, 109843f discloses5-bromo-2-carboxy-cinnamic acid which is obtained by oxidative cleavageof 6-bromo-2-naphthol and is then cyclized, reacted with PCl₅ and NH₃ togive the amide and subsequently, with ring enlargement, reacted in thepresence of NaOCI to give 6-bromo-isoquinolin- 1-one.

Also known from Chemical Abstracts 82, 1975, 31200n and 79, 1973,91891m, is the oxidative cleavage of 6-bromo-2-naphthol with formationof 5-bromo-2-carboxy-cinnamic acid, which leads, via a plurality ofsteps of amidation, Hoffmann rearrangement and cyclization, to thecorresponding substituted indoles.

WO 97/43287 A1 discloses, in a general manner, substituted cinnamicacids and cinnamic acid chlorides which may be substituted on the phenylring by a radical R¹ and one or two further radicals R², a large numberof meanings being possible for these radicals. Also described is thereaction of the substituted cinnamic acids and cinnamic acid chlorideswith other complex starting materials to give specific carbolinederivatives which are used as cGMP-PDE inhibitors for cardiovascularindications.

WO 96/04241 A1 discloses, in the form of preparation 45, a cinnamic acidwhich is substituted in one m-position of the 2-carboxyvinyl radical bymethyl carboxylate and in the other m-position by iodine. WO 96/04241 isfocused on the preparation of specific, pharmaceutically activebenzoylguanidine derivatives, in which the preparation 45 is also used.

EP-A-0 508 264 discloses a process for preparing broadly definedarylolefins which, in a general manner, also include substitutedcinnamic acids and cinnamic acid esters. The arylolefins that can beprepared are used in very different areas, for example as opticalbrighteners, as precursors for optical brighteners, as intermediates forpharmaceutics or as UV absorbers.

DESCRIPTION OF THE INVENTION

Accordingly, it was the object of the present invention to provideintermediates which can be used to synthesize substitutedindanonecarboxylic acid esters in a technically simple manner, whichdoes not involve any safety risks.

This object is achieved by substituted cinnamic acids and cinnamic acidesters of the formula (I)

where X represents F, Cl or J and R¹ and R² are identical or differentand represent hydrogen, an optionally substituted C₁-C₁₀-alkyl radicalor an optionally substituted benzyl radical.

These substituted cinnamic acids or cinnamic acid esters aredistinguished by the fact that, for the first time, they allow, in anunexpectedly simple two-step process, a low-cost synthesis ofsubstituted indanonecarboxylic acid esters.

In the substituted cinnamic acids or cinnamic acid esters, X representsF, Cl J, preferably chlorine.

R¹ and R² are identical or different and represent hydrogen, anoptionally substituted C₁-C₁₀-alkyl radical or an optionally substitutedbenzyl radical. Preferably, R¹ and R² independently of one anotherrepresent hydrogen, methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl,tert butyl, n-pentyl, i-pentyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl,n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl or i-decyl. In particular,R¹ and R² independently of one another represent hydrogen or methyl.

If the C₁-C₁₀-alkyl radical is substituted as radical R¹ or R², thesesubstituents can be halogen, hydroxyl or C₆-C₁₂-aryl radicals. Thebenzyl radical as radical R¹ or R² can be substituted by halogen,hydroxyl, C₁-C₁₀-alkyl or C₆-C₁₂-aryl radicals.

In the cinnamic acids or cinnamic acid esters of the formula (I), thesubstituent X is preferably in the 5-position to the acrylic acid oracrylic acid ester radical.

Preferred compounds of the formula (I) are methyl4-chloro-2-(3-methoxy-3-oxo-1-propenyl)benzoate,4-chloro-2-(3-methoxy-3-oxo-1 -propenyl)-benzoic acid,4-fluoro-2-(3-methoxy-3-oxo-1-propenyl)benzoic acid, methyl4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoate or4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoic acid.

The substituted cinnamic acids or cinnamic acid esters of the formula(I) can be prepared by a variation of the Heck reaction (Process A).

The invention provides a process for preparing the substituted cinnamicacids and cinnamic acid esters of the formula (I) by reacting diazoniumsalts of the formula (II0 with acrylic acid derivatives of the formula(III) in the presence of a palladium-containing catalyst, where X, R¹and R² are as defined in formula (I) and A- represents halide,preferably chloride or bromide, sulfate, hydrogen sulfate, nitrate,phosphate, acetate or tetrafluoroborate, characterized in that thereaction is carried out in the absence of bases. This synthesis route isparticularly advantageous and thus preferred.

X, R¹ and R² preferably have the meanings which have also been mentionedas being preferred for the formula (I). A- preferably representschloride, sulfate, hydrogen sulfate, acetate or tetrafluoroborate.

The reaction principle of this process A is generally known as Matsudavariant of the Heck reaction. According to EP-A-0 584 043, for example,compounds of the formula Ar—CHR_(a)—CHR_(b)R_(c) can be prepared in avery general manner, R_(a), R_(b) and R_(c) independently of one anotherrepresenting hydrogen or a substituent which is inert to hydrogenationand Ar representing an optionally substituted C₆-C₂₀-aryl- orC₃-C₂₀-heteroaryl radical. To this end, in a first step, 1 molarequivalent of the diazonium cation Ar—N₂ ⁺ is reacted with at least 1molar equivalent of a compound CR_(a)═CR_(b)RC with formation of thecompound Ar—CHR_(a)=CHR_(b)R_(c), the reaction being carried out in thepresence of a catalytic amount of a homogeneous palladium catalyst.Furthermore, addition of a base is a necessary requirement. Inparticular when the Heck reaction is carried out on an industrial scale,the addition of from 1 to 10 molar equivalents of this base involvesadditional costs and a complicated work-up of the reaction mixture. In asecond step, the compound Ar—CHR_(a)═CHR_(b)R_(c) is hydrogenated togive the compound Ar—CHR_(a)—CHR_(b)R_(c). This hydrogenation step ischaracterized in that the reaction is carried out in the presence ofcatalytic amounts of a heterogeneous palladium catalyst, which isobtained from the homogeneous palladium catalyst of the first step byreduction prior to the second step.

EP-A-0 584 043 discloses explicitly and especially only those compoundsAr—HR_(a)═CHR_(b)R_(c) and Ar—CHR_(a)—CHR_(b)R_(c) which carry asulfonic acid group and optionally other substituents on the arylradical Ar. However, EP-A-0 584 043 does not disclose the cinnamic acidsor cinnamic acid esters of the formula (I) according to the inventionwhich are substituted on the radical Ar=phenyl by a halogen radical anda carboxylic acid or carboxylic acid ester radical, nor their specificpreparation according to process A, nor their excellent suitability foruse as starting materials for the preparation of substitutedindanonecarboxylic acid esters. Compared to the process of EP-A-0 584043, process A is distinguished by the fact that it is possible toobtain excellent high yields even without the addition of a base, whichenhances the economic attraction of the process with respect to work-upand generation of waste water. It is even possible to carry out theprocess in a solution of mineral or sulfuric acid.

F EP-A-0 508 264, too, discloses the principle of process A, i.e. thepreparation, from aryldiazonium salts and olefins in the presence of apalladium catalyst, of the corresponding aryl olefins. However, as inthe case of EP-A-0 584 043, the emphasis of EP-A-0 508 264 is placed oncompounds which carry a sulfonic acid group on the aryl radical. Theselected cinnamic acids or cinnamic acid esters according to theinvention and their suitability for preparing substitutedindanonecarboxylic acid esters are not explicitly disclosed. Accordingto EP-A-0 508 264, too, in the Heck reaction bases are added and also,favorably, ligands, such as triarylphosphines orbis(diarylphosphine)alkanes capable of forming complexes with thepalladium or the palladium salts. In contrast, process A ischaracterized by the fact that the addition of such auxiliary ligands tothe catalyst is usually not required.

The Heck reaction according to variant A is carried out usingpalladium(II)salts, such as PdCl₂, PdBr₂, Pd(NO₃)₂, H₂PdCl₄,Pd(CH₃COO)₂, [PdCl₄]Na₂, [PdCl₄]Li_(2, [PdCl) ₄]K₂, or palladium(I)acetylacetonate. PdCl₂, Pd(CH₃COO)₂ and palladium(II) acetylacetonateare particularly preferred. Usually, 0.001-10 mol % of thepalladium-containing catalyst, based on the diazonium salt of theformula (II), are employed.

The reaction temperature for variant A should be below the decompositiontemperature of the diazonium ion; in general, variant A is carried outat from −20° C. to 100° C., preferably from 20 to 80° C. and inparticular from 40 to 65° C. The reaction can be carried out withaddition of suitable solvents; usually, water, alcohols, preferablymethanol, ethanol, propanol, i-propanol or butanol, formic acid,tetrahydrofuran or acetonitrile are added.

The diazonium salts of the formula (II) used in process A are obtainableby reacting halogenated anthranilic acid derivatives with sodium nitritein acidic aqueous solution or with methyl nitrite in acidic methanol. Ifsodium nitrite is used, preferably in aqueous solution acidified withsulfuric acid, small amounts of isopropanol may also additionally bepresent. If methyl nitrite in methanol acidified with sulfuric acid isused, the reaction is generally carried out anhydrous to avoidunnecessary hydrolysis of methyl nitrite. It is advantageous that noorganic solvents such as dimethylformamide (DMF), N-methylpyrrolidone(NMP) or dimethyl sulfoxide (DMSO) have to be used in thisdiazotization. Also advantageous are the low reaction temperatures. Thecinnamic acids or cinnamic acid esters of the formula (I) usuallyprecipitate from an aqueous reaction mixture or can be precipitated byadditional addition of water. The resulting solids can be dissolved forsubsequent reactions by adding organic solvents.

Instead of the diazonium salts of the formula (II), it is also possibleto react in the Heck coupling halogenated aromatic compounds of theformula (IV) with the acrylic acid derivatives of the formula (III)(Process B), X, R¹ and R² being as defined for formula (I). Y representsbromine or iodine. EP-A-0 688 757, too, discloses the reaction of suchhalogenated aromatic compounds with olefins, the palladium catalystsused being specific palladacycles, in particular μ-bridged dipalladiumcomplexes.

The present invention furthermore provides the use of substitutedcinnamic acids and cinnamic acid esters of the formula (I) for preparingsubstituted indanonecarboxylic acid esters of the formula (VII)

where

X and R² are as defined for formula (I).

A preferred embodiment of this use is characterized in that thesubstituted cinnamic acids and cinnamic acid esters of the formula (I)are, in a first step, hydrogenated with hydrogen in the presence of ahydrogenation catalyst, with formation of substituted arylpropionicacids of the formula (VIII),

which are then, in a second step, cyclized in the presence of a base,with formation of the substituted indanonecarboxylic acid esters of theformula (VIH), where X, R¹ and R² in the formulae (VII) and (VIII) eachhave the meanings mentioned for the formula (I).

The cinnamic acids or cinnamic acid esters of the formula (I) accordingto the invention obtained by process A or B can be introduced with orwithout prior isolation from the respective reaction mixtures into thefirst step for the synthesis of the substituted indanonecarboxylic acidesters. If, following their preparation by process A or B, the cinnamicacids or cinnamic acid esters of the formula (I) are not isolated, butthe entire reaction mixture is used for preparing the indanonecarboxylicacid esters of the formula (VII), the palladium catalyst of the Heckreaction acts as hydrogenation catalyst for the preparation of thearylpropionic acids of the formula (VIII). If the cinnamic acids orcinnamic acid esters are isolated as solids from the reaction mixture ofprocess A or B, a hydrogenation catalyst may be added for thehydrogenation to the arylpropionic acids. However, this is not necessaryin all cases if the isolated solid still contains small amounts of thecatalyst used in the Heck reaction. If a hydrogenation catalyst isadditionally added, it is usually a palladium or platinum catalystsupported on activated carbon.

The hydrogenation to the saturated arylpropionic acids of the formula(VIII) is carried out in the presence of hydrogen and, usually, water,mineral acids and/or alcohols as solvent.

The mineral acid present is usually sulfuric acid, unless the cinnamicacids or cinnamic acid esters are isolated from the reaction mixture ofthe preceding processes prior to their hydrogenation. The alcoholspresent can be, for example, methanol, ethanol, propanol, i-propanol orxylol.

The hydrogenation is usually carried out under a pressure of 1-100 bar.

The cyclization of the substituted arylpropionic acids of the formula(VIII) to the corresponding substituted indanonecarboxylic acid estersof the formula (VII) is carried out in the presence of a strong base anda suitable solvent. Usually, the strong base used is an alkali metalhydride, preferably sodium hydride, or an alkali metal alkoxide,preferably sodium alkoxide. Suitable solvents were found to be toluene,xylene, benzene or the alcohols which correspond to the alkali metalalkoxides. In particular, xylene or methanol is used. At a reactiontemperature of from 60 to 90° C. and a reaction pressure of from 100 to500 kPa, the reaction time is from 0.5 to 10 hours. Here, theindanonecarboxylic acid esters are obtained as alkali metal salt and areadditionally neutralized by addition of an acid, such as, for example,glacial acetic acid or dilute aqueous mineral acid, and then isolated byfiltration or extraction. For the reaction conditions of the cyclizationof the substituted arylpropionic acids of the formula (VIJI), referenceis otherwise made to the corresponding disclosure of WO 95/29 171, whichis expressly incorporated herein by way of reference.

The invention is further described in the following illustrativeexamples in which all parts and percentages are by weight unlessotherwise indicated.

EXAMPLE 1 Methyl 4-Chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate

Methyl nitrite is generated from 76 g of sodium nitrite in 55 ml ofmethanol and 183 ml of water using 80 ml of 50% strength sulfuric acid,and the methyl nitrite is introduced at from 10 to 15° C. into a mixtureof 171.5 g of 2-amino-4-chlorobenzoic acid, 800 ml of methanol and 200ml of concentrated sulfuric acid. The mixture is stirred for one hour,and 8 g of amidosulfonic acid are then added and excess methyl nitriteis removed from the reaction mixture by passing a stream of nitrogenover the mixture. 86 g of methyl acrylate and 666 mg of palladiumacetylacetonate are then added, and the mixture is heated at 40° C. for3 hours. 1600 ml of methanol are then added, and the mixture is heatedat the boil for a further 3 hours. Following addition a of 2500 ml ofice-water, the resulting precipitate is filtered off, washed with waterand then dried. This gives 207 g of methyl4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate of melting point 87-89°C.

EXAMPLE 2 4-Fluoro-2-(3-methoxy-3-oxo-1-propenyl)-benzoic Acid

At 0C, a solution of 0.52 g of sodium nitrite in 1 ml of water is addedwithin a period of 30 minutes to a mixture of 1 g of2-amino-4-fluorobenzoic acid, 15 ml of water and 6.24 ml of concentratedsulfuric acid. The mixture is then stirred for one hour. Followingaddition of 0.3 g of amidosulfonic acid, 0.7 g of methyl acrylate in 9ml of isopropanol are added dropwise, and 10 mg of palladiumacetylacetonate are added. After 4 hours at 40° C., 30 ml of water areadded and the resulting precipitate is filtered off. Drying gives 1.1 gof 4-fluoro-2-(3-methoxy-3-oxo-1-propenyl)-benzoic acid of melting point151-153° C.

EXAMPLE 3 Methyl 4-Chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate

At 2° C., a solution of 79.5 g of sodium nitrite in 150 ml of water isadded to a mixture of 185.5 g of methyl 2-amino-4-chlorobenzoate, 785 mlof water and 190.5 ml of concentrated sulfuric acid. Subsequently, themixture is stirred for 30 minutes, and 5.3 g of amidosulfonic acid arethen added. The resulting reaction mixture is added dropwise to 108.2 gof methyl acrylate. 766 mg of palladium acetylacetonate are then addedto the reaction mixture, which is then heated to 40° C. After a further3.5 hours at 40° C., the resulting precipitate is filtered off, giving,after drying, 248.3 g of methyl4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate of melting point 87-89°C.

EXAMPLE 4 Methyl 4-Chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoate

At 2° C., a solution of 5.96 g of sodium nitrite in 11.3 ml of water isadded to a mixture of 14 g of methyl 2-amino-4-chlorobenzoate, 59 ml ofwater and 14.3 ml of concentrated sulfuric acid. The reaction mixture issubsequently stirred for 20 minutes and then added a little at a time to6.9 g of acrylic acid, 57 mg of palladium acetylacetonate being addedafter the first portion. After 4 hours at 40° C., the precipitated solidis filtered off, giving, after washing and drying, 18.5 g of methyl4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoate.

EXAMPLE 5 4-Chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoic Acid

At 2° C., a solution of 2.98 g of sodium nitrite in 5.65 ml of water isadded to a mixture of 6.43 g of 2-amino-4-chlorobenzoic acid, 29.5 ml ofwater and 14.3 ml of concentrated sulfuric acid. 0.4 g of amidosulfonicacid are subsequently added, and this reaction mixture is then addeddropwise to 2.7 g of acrylic acid and 28.5 mg of palladiumacetylacetonate. After 4 hours at 40° C., the precipitated solid isfiltered off, giving 7.48 g of4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoic acid of melting point200-202° C.

Analogously, 6.7 g of product are obtained using 21 mg of palladiumacetate instead of 28.5 mg of palladium acetylacetonate.

EXAMPLE 6

Methyl 4-Chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoate

5 g of methyl 4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoate in theform of the isolated solid from Example 4 in 75 ml of methanol arehydrogenated without addition of hydrogenation catalyst, at from 20 to30° C. and a hydrogen pressure of 20 bar. Filtration through Celite® andremoval of the solvents under reduced pressure gives 3.3 g of productwhich, according to gas chromatography, contains 88% of methyl4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate.

The same product is obtained using, instead of methyl4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoate, methyl4-chloro-2-(3-methoxy-3-oxo-1 -propenyl)-benzoate from Example 1.

EXAMPLE 7 4-Chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoic Acid

Without addition of an additional hydrogenation catalyst, 43 g of4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoic acid in the form of theisolated solid from Example 5 in 400 ml of methanol are hydrogenated at40° C. and a hydrogen pressure of from 20 to 40 bar. Filtration throughCelite® and removal of the solvents under reduced pressure gives 35.3 gof product which, according to gas chromatography, contains 81 % of4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoic acid. The same productis obtained using, instead of4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoic acid,4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoic acid.

EXAMPLE 8 Methyl 4-Chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoate

26.1 g of the methyl 4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoateprepared according to Example 1 are taken up in 300 ml of methanol andtransferred into an autoclave and then hydrogenated at 30° C. and ahydrogen pressure of 30 bar for 5 h, until the theoretical amount ofhydrogen has been taken up. The substance contains the palladiumcatalyst required for the Heck coupling, so that separate addition of ahydrogenation catalyst can be dispensed with. The pressure is reduced to1 bar, and insoluble components are then filtered off. Solvent is thenremoved under reduced pressure until the hydrogenation productprecipitates. Recrystallization gives 21 g of methyl4-chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoate.

EXAMPLE 9 Methyl 4-Chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoate

26.1 g of the methyl 4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoateobtained according to Example 3 are taken up in 250 ml of methanol,about 1 g of activated carbon is added, the mixture is stirred underreflux and the hot mixture is filtered, this step removing the residualamounts of palladium catalyst from the Heck reaction. The filtrate,cooled again to room temperature, is then admixed with 1.5 g of a 5%strength platinum/carbon catalyst and hydrogenated at 30° C. and ahydrogen pressure of 5 bar for about 4 to 5 h, until the theoreticalamount of hydrogen has been taken up. The pressure is reduced, thecatalyst is filtered off and the solvent is removed from the mixture,thus giving 25.2 g of 4-chloro-2-(3-methoxy-3-oxo-1-propanyl)-benzoicacid ester.

EXAMPLE 10 2-Carboxymethyl-5-chloroindan-1-one

108 g of methyl 4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoate aredissolved in 300 ml of methanol, and 80 g of sodium methoxide are thenadded. The mixture is then heated at 70° C. and some of the methanol isdistilled off, such that the reaction mixture can still be stirred.After 2 h, 400 ml of toluene are added slowly, and the remainingmethanol is removed. The mixture is then stirred for another 0.5 h andthen cooled to room temperature. 10 g of acetic acid are then addeddropwise to the mixture, which is then diluted with 500 ml of water andadjusted to pH 4-5 using 1 N hydrochloric acid. The toluene phase isconcentrated until the product precipitates. Following filtration, theproduct can be recrystallized from hexane. This gives 93.5 g of2-carboxymethyl-5-chloroindan-1-one.

Although the present invention has been described in detail withreference to certain preferred versions thereof, other variations arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the versions contained therein.

What is claimed is:
 1. A substituted cinnamic acid or cinnamic acidester of the formula (I)

wherein X represents F, Cl or I and R¹ and R² are identical or differentand represent hydrogen, an optionally substituted C₁-C₁₀-alkyl radicalor an optionally substituted benzyl radical.
 2. The substituted cinnamicacid or cinnamic acid ester as claimed in claim 1, wherein X representschlorine and independently thereof R¹ and R² are identical or differentand represent hydrogen, methyl, ethyl, propyl, i-propyl, n-butyl,i-butyl, tert butyl, n-pentyl, i-pentyl, n-hexyl, i-hexyl, n-heptyl,i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl or i-decyl.
 3. Thesubstituted cinnamic acid or cinnamic acid ester as claimed in claim 1,wherein the C₁-C₁₀-alkyl radical as radical R¹ or R² is substituted byhalogen, hydroxyl or C₆-C₁₂-aryl radicals and independently thereof thebenzyl radical as radical R¹ or R² is substituted by halogen, hydroxyl,C₁-C₁₀-alkyl- or C₆-C₁₂aryl radicals.
 4. The substituted cinnamic acidor cinnamic acid ester as claimed in claim 1, wherein the cinnamic acidor cinnamic acid ester is methyl4-chloro-2-(3-methoxy-3-oxo-1-propenyl)benzoate,4-chloro-2-(3-methoxy-3-oxo-1-propenyl)-benzoic acid,4-fluoro-2-(3-methoxy-3-oxo-1-propenyl)benzoic acid, methyl4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoate or4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoic acid.
 5. A process forpreparing a substituted cinnamic acid or a cinnamic acid ester of theformula (I)

wherein X represents F, Cl or I and R¹ and R² are identical or differentand represent hydrogen, an optionally substituted C₁-C₁₀-alkyl radicalor an optionally substituted benzyl radical; comprising reactingdiazonium salts of the formula (II)

with acrylic acid derivatives of the formula (III)

 in the presence of a palladium-containing catalyst, wherein X, R¹ andR² are as defined in formula (I) and AΘ represents a halide, a sulfate,hydrogen sulfate, a nitrate, a phosphate, an acetate ortetrafluoro-borate, and wherein the reaction is carried out in theabsence of bases.
 6. The process of claim 5, wherein thepalladium-containing catalyst used is a palladium(II) salt.
 7. Theprocess according to claim 5, wherein from about 0.001 to about 10 mol %of the palladium-containing catalyst, based on the diazonium salt of theformula (II), are used and, independently thereof, the process iscarried out at a temperature that ranges from about −20 to about 100° C.8. A process for preparing a substituted indanonecarboxylic acid esterof the formula (VII)

wherein X represents F, Cl or I and R¹ and R² are identical or differentand represent hydrogen, an optionally substituted C₁-C₁₀-alkyl radicalor an optionally substituted benzylradical, comprising (A)hydrogenating, in the presence of a hydrogenation catalyst, asubstituted cinnamic acid or cinnamic acid ester of the formula (I)

 wherein X represents F, Cl or I and R¹ and R² are identical ordifferent and represent hydrogen, an optionally substituted C₁-C₁₀-alkylradical or an optionally substituted benzyl radical; and forming asubstituted arylpropionic acid of the formula (VIII),

 and (B) cyclizing the substituted arylpropionic of formula (VIII) inthe presence of a base.